#!/usr/bin/env python3
"""The multi-user notebook application"""

# Copyright (c) Jupyter Development Team.
# Distributed under the terms of the Modified BSD License.

import atexit
import binascii
import logging
import os
import signal
import socket
import sys
import threading
from datetime import datetime
from distutils.version import LooseVersion as V
from getpass import getuser
from subprocess import Popen

if sys.version_info[:2] < (3,3):
    raise ValueError("Python < 3.3 not supported: %s" % sys.version)

from jinja2 import Environment, FileSystemLoader

from sqlalchemy.exc import OperationalError
from sqlalchemy.orm import scoped_session

import tornado.httpserver
import tornado.options
from tornado.httpclient import HTTPError
from tornado.ioloop import IOLoop, PeriodicCallback
from tornado.log import app_log, access_log, gen_log
from tornado import gen, web

from traitlets import (
    Unicode, Integer, Dict, TraitError, List, Bool, Any,
    Type, Set, Instance, Bytes, Float,
)
from traitlets.config import Application, catch_config_error

here = os.path.dirname(__file__)

import jupyterhub
from . import handlers, apihandlers
from .handlers.static import CacheControlStaticFilesHandler

from . import orm
from ._data import DATA_FILES_PATH
from .log import CoroutineLogFormatter, log_request
from .traitlets import URLPrefix, Command
from .utils import (
    url_path_join,
    ISO8601_ms, ISO8601_s,
)
# classes for config
from .auth import Authenticator, PAMAuthenticator
from .spawner import Spawner, LocalProcessSpawner

common_aliases = {
    'log-level': 'Application.log_level',
    'f': 'JupyterHub.config_file',
    'config': 'JupyterHub.config_file',
    'db': 'JupyterHub.db_url',
}


aliases = {
    'base-url': 'JupyterHub.base_url',
    'y': 'JupyterHub.answer_yes',
    'ssl-key': 'JupyterHub.ssl_key',
    'ssl-cert': 'JupyterHub.ssl_cert',
    'ip': 'JupyterHub.ip',
    'port': 'JupyterHub.port',
    'pid-file': 'JupyterHub.pid_file',
    'log-file': 'JupyterHub.extra_log_file',
}
token_aliases = {}
token_aliases.update(common_aliases)
aliases.update(common_aliases)

flags = {
    'debug': ({'Application' : {'log_level': logging.DEBUG}},
        "set log level to logging.DEBUG (maximize logging output)"),
    'generate-config': ({'JupyterHub': {'generate_config': True}},
        "generate default config file"),
    'no-db': ({'JupyterHub': {'db_url': 'sqlite:///:memory:'}},
        "disable persisting state database to disk"
    ),
}

SECRET_BYTES = 2048 # the number of bytes to use when generating new secrets

class NewToken(Application):
    """Generate and print a new API token"""
    name = 'jupyterhub-token'
    description = """Generate and return new API token for a user.
    
    Usage:
    
        jupyterhub token [username]
    """
    
    examples = """
        $> jupyterhub token kaylee
        ab01cd23ef45
    """
    
    name = Unicode(getuser())
    
    aliases = token_aliases
    classes = []
    
    def parse_command_line(self, argv=None):
        super().parse_command_line(argv=argv)
        if not self.extra_args:
            return
        if len(self.extra_args) > 1:
            print("Must specify exactly one username", file=sys.stderr)
            self.exit(1)
        self.name = self.extra_args[0]
    
    def start(self):
        hub = JupyterHub(parent=self)
        hub.load_config_file(hub.config_file)
        hub.init_db()
        hub.hub = hub.db.query(orm.Hub).first()
        hub.init_users()
        user = orm.User.find(hub.db, self.name)
        if user is None:
            print("No such user: %s" % self.name, file=sys.stderr)
            self.exit(1)
        token = user.new_api_token()
        print(token)


class JupyterHub(Application):
    """An Application for starting a Multi-User Jupyter Notebook server."""
    name = 'jupyterhub'
    version = jupyterhub.__version__
    
    description = """Start a multi-user Jupyter Notebook server
    
    Spawns a configurable-http-proxy and multi-user Hub,
    which authenticates users and spawns single-user Notebook servers
    on behalf of users.
    """
    
    examples = """
    
    generate default config file:
    
        jupyterhub --generate-config -f /etc/jupyterhub/jupyterhub.py
    
    spawn the server on 10.0.1.2:443 with https:
    
        jupyterhub --ip 10.0.1.2 --port 443 --ssl-key my_ssl.key --ssl-cert my_ssl.cert
    """
    
    aliases = Dict(aliases)
    flags = Dict(flags)
    
    subcommands = {
        'token': (NewToken, "Generate an API token for a user")
    }
    
    classes = List([
        Spawner,
        LocalProcessSpawner,
        Authenticator,
        PAMAuthenticator,
    ])
    
    config_file = Unicode('jupyterhub_config.py', config=True,
        help="The config file to load",
    )
    generate_config = Bool(False, config=True,
        help="Generate default config file",
    )
    answer_yes = Bool(False, config=True,
        help="Answer yes to any questions (e.g. confirm overwrite)"
    )
    pid_file = Unicode('', config=True,
        help="""File to write PID
        Useful for daemonizing jupyterhub.
        """
    )
    cookie_max_age_days = Float(14, config=True,
        help="""Number of days for a login cookie to be valid.
        Default is two weeks.
        """
    )
    last_activity_interval = Integer(300, config=True,
        help="Interval (in seconds) at which to update last-activity timestamps."
    )
    proxy_check_interval = Integer(30, config=True,
        help="Interval (in seconds) at which to check if the proxy is running."
    )
    
    data_files_path = Unicode(DATA_FILES_PATH, config=True,
        help="The location of jupyterhub data files (e.g. /usr/local/share/jupyter/hub)"
    )

    template_paths = List(
        config=True,
        help="Paths to search for jinja templates.",
    )

    def _template_paths_default(self):
        return [os.path.join(self.data_files_path, 'templates')]

    ssl_key = Unicode('', config=True,
        help="""Path to SSL key file for the public facing interface of the proxy
        
        Use with ssl_cert
        """
    )
    ssl_cert = Unicode('', config=True,
        help="""Path to SSL certificate file for the public facing interface of the proxy
        
        Use with ssl_key
        """
    )
    ip = Unicode('', config=True,
        help="The public facing ip of the proxy"
    )
    port = Integer(8000, config=True,
        help="The public facing port of the proxy"
    )
    base_url = URLPrefix('/', config=True,
        help="The base URL of the entire application"
    )
    
    jinja_environment_options = Dict(config=True,
        help="Supply extra arguments that will be passed to Jinja environment."
    )
    
    proxy_cmd = Command('configurable-http-proxy', config=True,
        help="""The command to start the http proxy.
        
        Only override if configurable-http-proxy is not on your PATH
        """
    )
    debug_proxy = Bool(False, config=True, help="show debug output in configurable-http-proxy")
    proxy_auth_token = Unicode(config=True,
        help="""The Proxy Auth token.

        Loaded from the CONFIGPROXY_AUTH_TOKEN env variable by default.
        """
    )
    def _proxy_auth_token_default(self):
        token = os.environ.get('CONFIGPROXY_AUTH_TOKEN', None)
        if not token:
            self.log.warn('\n'.join([
                "",
                "Generating CONFIGPROXY_AUTH_TOKEN. Restarting the Hub will require restarting the proxy.",
                "Set CONFIGPROXY_AUTH_TOKEN env or JupyterHub.proxy_auth_token config to avoid this message.",
                "",
            ]))
            token = orm.new_token()
        return token
    
    proxy_api_ip = Unicode('localhost', config=True,
        help="The ip for the proxy API handlers"
    )
    proxy_api_port = Integer(config=True,
        help="The port for the proxy API handlers"
    )
    def _proxy_api_port_default(self):
        return self.port + 1
    
    hub_port = Integer(8081, config=True,
        help="The port for this process"
    )
    hub_ip = Unicode('localhost', config=True,
        help="The ip for this process"
    )
    
    hub_prefix = URLPrefix('/hub/', config=True,
        help="The prefix for the hub server. Must not be '/'"
    )
    def _hub_prefix_default(self):
        return url_path_join(self.base_url, '/hub/')
    
    def _hub_prefix_changed(self, name, old, new):
        if new == '/':
            raise TraitError("'/' is not a valid hub prefix")
        if not new.startswith(self.base_url):
            self.hub_prefix = url_path_join(self.base_url, new)
    
    cookie_secret = Bytes(config=True, env='JPY_COOKIE_SECRET',
        help="""The cookie secret to use to encrypt cookies.

        Loaded from the JPY_COOKIE_SECRET env variable by default.
        """
    )
    
    cookie_secret_file = Unicode('jupyterhub_cookie_secret', config=True,
        help="""File in which to store the cookie secret."""
    )
    
    authenticator_class = Type(PAMAuthenticator, Authenticator,
        config=True,
        help="""Class for authenticating users.
        
        This should be a class with the following form:
        
        - constructor takes one kwarg: `config`, the IPython config object.
        
        - is a tornado.gen.coroutine
        - returns username on success, None on failure
        - takes two arguments: (handler, data),
          where `handler` is the calling web.RequestHandler,
          and `data` is the POST form data from the login page.
        """
    )
    
    authenticator = Instance(Authenticator)
    def _authenticator_default(self):
        return self.authenticator_class(parent=self, db=self.db)

    # class for spawning single-user servers
    spawner_class = Type(LocalProcessSpawner, Spawner,
        config=True,
        help="""The class to use for spawning single-user servers.
        
        Should be a subclass of Spawner.
        """
    )
    
    db_url = Unicode('sqlite:///jupyterhub.sqlite', config=True,
        help="url for the database. e.g. `sqlite:///jupyterhub.sqlite`"
    )
    def _db_url_changed(self, name, old, new):
        if '://' not in new:
            # assume sqlite, if given as a plain filename
            self.db_url = 'sqlite:///%s' % new

    db_kwargs = Dict(config=True,
        help="""Include any kwargs to pass to the database connection.
        See sqlalchemy.create_engine for details.
        """
    )

    reset_db = Bool(False, config=True,
        help="Purge and reset the database."
    )
    debug_db = Bool(False, config=True,
        help="log all database transactions. This has A LOT of output"
    )
    session_factory = Any()
    
    admin_access = Bool(False, config=True,
        help="""Grant admin users permission to access single-user servers.
        
        Users should be properly informed if this is enabled.
        """
    )
    admin_users = Set(config=True,
        help="""DEPRECATED, use Authenticator.admin_users instead."""
    )
    
    tornado_settings = Dict(config=True)
    
    cleanup_servers = Bool(True, config=True,
        help="""Whether to shutdown single-user servers when the Hub shuts down.
        
        Disable if you want to be able to teardown the Hub while leaving the single-user servers running.
        
        If both this and cleanup_proxy are False, sending SIGINT to the Hub will
        only shutdown the Hub, leaving everything else running.
        
        The Hub should be able to resume from database state.
        """
    )

    cleanup_proxy = Bool(True, config=True,
        help="""Whether to shutdown the proxy when the Hub shuts down.
        
        Disable if you want to be able to teardown the Hub while leaving the proxy running.
        
        Only valid if the proxy was starting by the Hub process.
        
        If both this and cleanup_servers are False, sending SIGINT to the Hub will
        only shutdown the Hub, leaving everything else running.
        
        The Hub should be able to resume from database state.
        """
    )
    
    handlers = List()
    
    _log_formatter_cls = CoroutineLogFormatter
    http_server = None
    proxy_process = None
    io_loop = None
    
    def _log_level_default(self):
        return logging.INFO
    
    def _log_datefmt_default(self):
        """Exclude date from default date format"""
        return "%Y-%m-%d %H:%M:%S"

    def _log_format_default(self):
        """override default log format to include time"""
        return "%(color)s[%(levelname)1.1s %(asctime)s.%(msecs).03d %(name)s %(module)s:%(lineno)d]%(end_color)s %(message)s"

    extra_log_file = Unicode(
        "",
        config=True,
        help="Set a logging.FileHandler on this file."
    )
    extra_log_handlers = List(
        Instance(logging.Handler),
        config=True,
        help="Extra log handlers to set on JupyterHub logger",
    )

    def init_logging(self):
        # This prevents double log messages because tornado use a root logger that
        # self.log is a child of. The logging module dipatches log messages to a log
        # and all of its ancenstors until propagate is set to False.
        self.log.propagate = False

        if self.extra_log_file:
            self.extra_log_handlers.append(
                logging.FileHandler(self.extra_log_file)
            )

        _formatter = self._log_formatter_cls(
            fmt=self.log_format,
            datefmt=self.log_datefmt,
        )
        for handler in self.extra_log_handlers:
            if handler.formatter is None:
                handler.setFormatter(_formatter)
            self.log.addHandler(handler)

        # hook up tornado 3's loggers to our app handlers
        for log in (app_log, access_log, gen_log):
            # ensure all log statements identify the application they come from
            log.name = self.log.name
        logger = logging.getLogger('tornado')
        logger.propagate = True
        logger.parent = self.log
        logger.setLevel(self.log.level)

    def init_ports(self):
        if self.hub_port == self.port:
            raise TraitError("The hub and proxy cannot both listen on port %i" % self.port)
        if self.hub_port == self.proxy_api_port:
            raise TraitError("The hub and proxy API cannot both listen on port %i" % self.hub_port)
        if self.proxy_api_port == self.port:
            raise TraitError("The proxy's public and API ports cannot both be %i" % self.port)
    
    @staticmethod
    def add_url_prefix(prefix, handlers):
        """add a url prefix to handlers"""
        for i, tup in enumerate(handlers):
            lis = list(tup)
            lis[0] = url_path_join(prefix, tup[0])
            handlers[i] = tuple(lis)
        return handlers
    
    def init_handlers(self):
        h = []
        h.extend(handlers.default_handlers)
        h.extend(apihandlers.default_handlers)
        # load handlers from the authenticator
        h.extend(self.authenticator.get_handlers(self))

        self.handlers = self.add_url_prefix(self.hub_prefix, h)

        # some extra handlers, outside hub_prefix
        self.handlers.extend([
            (r"%s" % self.hub_prefix.rstrip('/'), web.RedirectHandler,
                {
                    "url": self.hub_prefix,
                    "permanent": False,
                }
            ),
            (r"(?!%s).*" % self.hub_prefix, handlers.PrefixRedirectHandler),
            (r'(.*)', handlers.Template404),
        ])
    
    def _check_db_path(self, path):
        """More informative log messages for failed filesystem access"""
        path = os.path.abspath(path)
        parent, fname = os.path.split(path)
        user = getuser()
        if not os.path.isdir(parent):
            self.log.error("Directory %s does not exist", parent)
        if os.path.exists(parent) and not os.access(parent, os.W_OK):
            self.log.error("%s cannot create files in %s", user, parent)
        if os.path.exists(path) and not os.access(path, os.W_OK):
            self.log.error("%s cannot edit %s", user, path)
    
    def init_secrets(self):
        trait_name = 'cookie_secret'
        trait = self.traits()[trait_name]
        env_name = trait.get_metadata('env')
        secret_file = os.path.abspath(
            os.path.expanduser(self.cookie_secret_file)
        )
        secret = self.cookie_secret
        secret_from = 'config'
        # load priority: 1. config, 2. env, 3. file
        if not secret and os.environ.get(env_name):
            secret_from = 'env'
            self.log.info("Loading %s from env[%s]", trait_name, env_name)
            secret = binascii.a2b_hex(os.environ[env_name])
        if not secret and os.path.exists(secret_file):
            secret_from = 'file'
            perm = os.stat(secret_file).st_mode
            if perm & 0o077:
                self.log.error("Bad permissions on %s", secret_file)
            else:
                self.log.info("Loading %s from %s", trait_name, secret_file)
                with open(secret_file) as f:
                    b64_secret = f.read()
                try:
                    secret = binascii.a2b_base64(b64_secret)
                except Exception as e:
                    self.log.error("%s does not contain b64 key: %s", secret_file, e)
        if not secret:
            secret_from = 'new'
            self.log.debug("Generating new %s", trait_name)
            secret = os.urandom(SECRET_BYTES)
        
        if secret_file and secret_from == 'new':
            # if we generated a new secret, store it in the secret_file
            self.log.info("Writing %s to %s", trait_name, secret_file)
            b64_secret = binascii.b2a_base64(secret).decode('ascii')
            with open(secret_file, 'w') as f:
                f.write(b64_secret)
            try:
                os.chmod(secret_file, 0o600)
            except OSError:
                self.log.warn("Failed to set permissions on %s", secret_file)
        # store the loaded trait value
        self.cookie_secret = secret
    
    # thread-local storage of db objects
    _local = Instance(threading.local, ())
    @property
    def db(self):
        if not hasattr(self._local, 'db'):
            self._local.db = scoped_session(self.session_factory)()
        return self._local.db
    
    @property
    def hub(self):
        if not getattr(self._local, 'hub', None):
            q = self.db.query(orm.Hub)
            assert q.count() <= 1
            self._local.hub = q.first()
        return self._local.hub
    
    @hub.setter
    def hub(self, hub):
        self._local.hub = hub
    
    @property
    def proxy(self):
        if not getattr(self._local, 'proxy', None):
            q = self.db.query(orm.Proxy)
            assert q.count() <= 1
            p = self._local.proxy = q.first()
            if p:
                p.auth_token = self.proxy_auth_token
        return self._local.proxy
    
    @proxy.setter
    def proxy(self, proxy):
        self._local.proxy = proxy
    
    def init_db(self):
        """Create the database connection"""
        self.log.debug("Connecting to db: %s", self.db_url)
        try:
            self.session_factory = orm.new_session_factory(
                self.db_url,
                reset=self.reset_db,
                echo=self.debug_db,
                **self.db_kwargs
            )
            # trigger constructing thread local db property
            _ = self.db
        except OperationalError as e:
            self.log.error("Failed to connect to db: %s", self.db_url)
            self.log.debug("Database error was:", exc_info=True)
            if self.db_url.startswith('sqlite:///'):
                self._check_db_path(self.db_url.split(':///', 1)[1])
            self.exit(1)
    
    def init_hub(self):
        """Load the Hub config into the database"""
        self.hub = self.db.query(orm.Hub).first()
        if self.hub is None:
            self.hub = orm.Hub(
                server=orm.Server(
                    ip=self.hub_ip,
                    port=self.hub_port,
                    base_url=self.hub_prefix,
                    cookie_name='jupyter-hub-token',
                )
            )
            self.db.add(self.hub)
        else:
            server = self.hub.server
            server.ip = self.hub_ip
            server.port = self.hub_port
            server.base_url = self.hub_prefix

        self.db.commit()
    
    @gen.coroutine
    def init_users(self):
        """Load users into and from the database"""
        db = self.db
        
        if self.admin_users and not self.authenticator.admin_users:
            self.log.warn(
                "\nJupyterHub.admin_users is deprecated."
                "\nUse Authenticator.admin_users instead."
            )
            self.authenticator.admin_users = self.admin_users
        admin_users = self.authenticator.admin_users
        
        if not admin_users:
            # add current user as admin if there aren't any others
            admins = db.query(orm.User).filter(orm.User.admin==True)
            if admins.first() is None:
                admin_users.add(getuser())
        
        new_users = []

        for name in admin_users:
            # ensure anyone specified as admin in config is admin in db
            user = orm.User.find(db, name)
            if user is None:
                user = orm.User(name=name, admin=True)
                new_users.append(user)
                db.add(user)
            else:
                user.admin = True

        # the admin_users config variable will never be used after this point.
        # only the database values will be referenced.

        whitelist = self.authenticator.whitelist

        if not whitelist:
            self.log.info("Not using whitelist. Any authenticated user will be allowed.")

        # add whitelisted users to the db
        for name in whitelist:
            user = orm.User.find(db, name)
            if user is None:
                user = orm.User(name=name)
                new_users.append(user)
                db.add(user)

        if whitelist:
            # fill the whitelist with any users loaded from the db,
            # so we are consistent in both directions.
            # This lets whitelist be used to set up initial list,
            # but changes to the whitelist can occur in the database,
            # and persist across sessions.
            for user in db.query(orm.User):
                whitelist.add(user.name)

        # The whitelist set and the users in the db are now the same.
        # From this point on, any user changes should be done simultaneously
        # to the whitelist set and user db, unless the whitelist is empty (all users allowed).

        db.commit()
        
        for user in new_users:
            yield gen.maybe_future(self.authenticator.add_user(user))
        db.commit()
    
    @gen.coroutine
    def init_spawners(self):
        db = self.db
        
        user_summaries = ['']
        def _user_summary(user):
            parts = ['{0: >8}'.format(user.name)]
            if user.admin:
                parts.append('admin')
            if user.server:
                parts.append('running at %s' % user.server)
            return ' '.join(parts)
            
        @gen.coroutine
        def user_stopped(user):
            status = yield user.spawner.poll()
            self.log.warn("User %s server stopped with exit code: %s",
                user.name, status,
            )
            yield self.proxy.delete_user(user)
            yield user.stop()
        
        for user in db.query(orm.User):
            if not user.state:
                # without spawner state, server isn't valid
                user.server = None
                user_summaries.append(_user_summary(user))
                continue
            self.log.debug("Loading state for %s from db", user.name)
            user.spawner = spawner = self.spawner_class(
                user=user, hub=self.hub, config=self.config, db=self.db,
            )
            status = yield spawner.poll()
            if status is None:
                self.log.info("%s still running", user.name)
                spawner.add_poll_callback(user_stopped, user)
                spawner.start_polling()
            else:
                # user not running. This is expected if server is None,
                # but indicates the user's server died while the Hub wasn't running
                # if user.server is defined.
                log = self.log.warn if user.server else self.log.debug
                log("%s not running.", user.name)
                user.server = None

            user_summaries.append(_user_summary(user))

        self.log.debug("Loaded users: %s", '\n'.join(user_summaries))
        db.commit()

    def init_proxy(self):
        """Load the Proxy config into the database"""
        self.proxy = self.db.query(orm.Proxy).first()
        if self.proxy is None:
            self.proxy = orm.Proxy(
                public_server=orm.Server(),
                api_server=orm.Server(),
            )
            self.db.add(self.proxy)
            self.db.commit()
        self.proxy.auth_token = self.proxy_auth_token # not persisted
        self.proxy.log = self.log
        self.proxy.public_server.ip = self.ip
        self.proxy.public_server.port = self.port
        self.proxy.api_server.ip = self.proxy_api_ip
        self.proxy.api_server.port = self.proxy_api_port
        self.proxy.api_server.base_url = '/api/routes/'
        self.db.commit()
    
    @gen.coroutine
    def start_proxy(self):
        """Actually start the configurable-http-proxy"""
        # check for proxy
        if self.proxy.public_server.is_up() or self.proxy.api_server.is_up():
            # check for *authenticated* access to the proxy (auth token can change)
            try:
                yield self.proxy.get_routes()
            except (HTTPError, OSError, socket.error) as e:
                if isinstance(e, HTTPError) and e.code == 403:
                    msg = "Did CONFIGPROXY_AUTH_TOKEN change?"
                else:
                    msg = "Is something else using %s?" % self.proxy.public_server.bind_url
                self.log.error("Proxy appears to be running at %s, but I can't access it (%s)\n%s",
                    self.proxy.public_server.bind_url, e, msg)
                self.exit(1)
                return
            else:
                self.log.info("Proxy already running at: %s", self.proxy.public_server.bind_url)
            self.proxy_process = None
            return

        env = os.environ.copy()
        env['CONFIGPROXY_AUTH_TOKEN'] = self.proxy.auth_token
        cmd = self.proxy_cmd + [
            '--ip', self.proxy.public_server.ip,
            '--port', str(self.proxy.public_server.port),
            '--api-ip', self.proxy.api_server.ip,
            '--api-port', str(self.proxy.api_server.port),
            '--default-target', self.hub.server.host,
        ]
        if self.debug_proxy:
            cmd.extend(['--log-level', 'debug'])
        if self.ssl_key:
            cmd.extend(['--ssl-key', self.ssl_key])
        if self.ssl_cert:
            cmd.extend(['--ssl-cert', self.ssl_cert])
        self.log.info("Starting proxy @ %s", self.proxy.public_server.bind_url)
        self.log.debug("Proxy cmd: %s", cmd)
        try:
            self.proxy_process = Popen(cmd, env=env)
        except FileNotFoundError as e:
            self.log.error(
                "Failed to find proxy %r\n"
                "The proxy can be installed with `npm install -g configurable-http-proxy`"
                 % self.proxy_cmd
            )
            self.exit(1)
        def _check():
            status = self.proxy_process.poll()
            if status is not None:
                e = RuntimeError("Proxy failed to start with exit code %i" % status)
                # py2-compatible `raise e from None`
                e.__cause__ = None
                raise e
        
        for server in (self.proxy.public_server, self.proxy.api_server):
            for i in range(10):
                _check()
                try:
                    yield server.wait_up(1)
                except TimeoutError:
                    continue
                else:
                    break
            yield server.wait_up(1)
        self.log.debug("Proxy started and appears to be up")
    
    @gen.coroutine
    def check_proxy(self):
        if self.proxy_process.poll() is None:
            return
        self.log.error("Proxy stopped with exit code %r",
            'unknown' if self.proxy_process is None else self.proxy_process.poll()
        )
        yield self.start_proxy()
        self.log.info("Setting up routes on new proxy")
        yield self.proxy.add_all_users()
        self.log.info("New proxy back up, and good to go")
    
    def init_tornado_settings(self):
        """Set up the tornado settings dict."""
        base_url = self.hub.server.base_url
        jinja_env = Environment(
            loader=FileSystemLoader(self.template_paths),
            **self.jinja_environment_options
        )
        
        login_url = self.authenticator.login_url(base_url)
        logout_url = self.authenticator.logout_url(base_url)
        
        # if running from git, disable caching of require.js
        # otherwise cache based on server start time
        parent = os.path.dirname(os.path.dirname(jupyterhub.__file__))
        if os.path.isdir(os.path.join(parent, '.git')):
            version_hash = ''
        else:
            version_hash=datetime.now().strftime("%Y%m%d%H%M%S"),
        
        settings = dict(
            log_function=log_request,
            config=self.config,
            log=self.log,
            db=self.db,
            proxy=self.proxy,
            hub=self.hub,
            admin_users=self.authenticator.admin_users,
            admin_access=self.admin_access,
            authenticator=self.authenticator,
            spawner_class=self.spawner_class,
            base_url=self.base_url,
            cookie_secret=self.cookie_secret,
            cookie_max_age_days=self.cookie_max_age_days,
            login_url=login_url,
            logout_url=logout_url,
            static_path=os.path.join(self.data_files_path, 'static'),
            static_url_prefix=url_path_join(self.hub.server.base_url, 'static/'),
            static_handler_class=CacheControlStaticFilesHandler,
            template_path=self.template_paths,
            jinja2_env=jinja_env,
            version_hash=version_hash,
        )
        # allow configured settings to have priority
        settings.update(self.tornado_settings)
        self.tornado_settings = settings
    
    def init_tornado_application(self):
        """Instantiate the tornado Application object"""
        self.tornado_application = web.Application(self.handlers, **self.tornado_settings)
    
    def write_pid_file(self):
        pid = os.getpid()
        if self.pid_file:
            self.log.debug("Writing PID %i to %s", pid, self.pid_file)
            with open(self.pid_file, 'w') as f:
                f.write('%i' % pid)
    
    @gen.coroutine
    @catch_config_error
    def initialize(self, *args, **kwargs):
        super().initialize(*args, **kwargs)
        if self.generate_config or self.subapp:
            return
        self.load_config_file(self.config_file)
        self.init_logging()
        if 'JupyterHubApp' in self.config:
            self.log.warn("Use JupyterHub in config, not JupyterHubApp. Outdated config:\n%s",
                '\n'.join('JupyterHubApp.{key} = {value!r}'.format(key=key, value=value)
                    for key, value in self.config.JupyterHubApp.items()
                )
            )
            cfg = self.config.copy()
            cfg.JupyterHub.merge(cfg.JupyterHubApp)
            self.update_config(cfg)
        self.write_pid_file()
        self.init_ports()
        self.init_secrets()
        self.init_db()
        self.init_hub()
        self.init_proxy()
        yield self.init_users()
        yield self.init_spawners()
        self.init_handlers()
        self.init_tornado_settings()
        self.init_tornado_application()
    
    @gen.coroutine
    def cleanup(self):
        """Shutdown our various subprocesses and cleanup runtime files."""
        
        futures = []
        if self.cleanup_servers:
            self.log.info("Cleaning up single-user servers...")
            # request (async) process termination
            for user in self.db.query(orm.User):
                if user.spawner is not None:
                    futures.append(user.stop())
        else:
            self.log.info("Leaving single-user servers running")
        
        # clean up proxy while SUS are shutting down
        if self.cleanup_proxy:
            if self.proxy_process:
                self.log.info("Cleaning up proxy[%i]...", self.proxy_process.pid)
                if self.proxy_process.poll() is None:
                    try:
                        self.proxy_process.terminate()
                    except Exception as e:
                        self.log.error("Failed to terminate proxy process: %s", e)
            else:
                self.log.info("I didn't start the proxy, I can't clean it up")
        else:
            self.log.info("Leaving proxy running")
        
        
        # wait for the requests to stop finish:
        for f in futures:
            try:
                yield f
            except Exception as e:
                self.log.error("Failed to stop user: %s", e)
        
        self.db.commit()
        
        if self.pid_file and os.path.exists(self.pid_file):
            self.log.info("Cleaning up PID file %s", self.pid_file)
            os.remove(self.pid_file)
        
        # finally stop the loop once we are all cleaned up
        self.log.info("...done")
    
    def write_config_file(self):
        """Write our default config to a .py config file"""
        if os.path.exists(self.config_file) and not self.answer_yes:
            answer = ''
            def ask():
                prompt = "Overwrite %s with default config? [y/N]" % self.config_file
                try:
                    return input(prompt).lower() or 'n'
                except KeyboardInterrupt:
                    print('') # empty line
                    return 'n'
            answer = ask()
            while not answer.startswith(('y', 'n')):
                print("Please answer 'yes' or 'no'")
                answer = ask()
            if answer.startswith('n'):
                return
        
        config_text = self.generate_config_file()
        if isinstance(config_text, bytes):
            config_text = config_text.decode('utf8')
        print("Writing default config to: %s" % self.config_file)
        with open(self.config_file, mode='w') as f:
            f.write(config_text)
    
    @gen.coroutine
    def update_last_activity(self):
        """Update User.last_activity timestamps from the proxy"""
        routes = yield self.proxy.get_routes()
        for prefix, route in routes.items():
            if 'user' not in route:
                # not a user route, ignore it
                continue
            user = orm.User.find(self.db, route['user'])
            if user is None:
                self.log.warn("Found no user for route: %s", route)
                continue
            try:
                dt = datetime.strptime(route['last_activity'], ISO8601_ms)
            except Exception:
                dt = datetime.strptime(route['last_activity'], ISO8601_s)
            user.last_activity = max(user.last_activity, dt)

        self.db.commit()
        yield self.proxy.check_routes(routes)
    
    @gen.coroutine
    def start(self):
        """Start the whole thing"""
        self.io_loop = loop = IOLoop.current()
        
        if self.subapp:
            self.subapp.start()
            loop.stop()
            return
        
        if self.generate_config:
            self.write_config_file()
            loop.stop()
            return
        
        # start the webserver
        self.http_server = tornado.httpserver.HTTPServer(self.tornado_application, xheaders=True)
        try:
            self.http_server.listen(self.hub_port, address=self.hub_ip)
        except Exception:
            self.log.error("Failed to bind hub to %s", self.hub.server.bind_url)
            raise
        else:
            self.log.info("Hub API listening on %s", self.hub.server.bind_url)
        
        # start the proxy
        try:
            yield self.start_proxy()
        except Exception as e:
            self.log.critical("Failed to start proxy", exc_info=True)
            self.exit(1)
            return
        
        loop.add_callback(self.proxy.add_all_users)
        
        if self.proxy_process:
            # only check / restart the proxy if we started it in the first place.
            # this means a restarted Hub cannot restart a Proxy that its
            # predecessor started.
            pc = PeriodicCallback(self.check_proxy, 1e3 * self.proxy_check_interval)
            pc.start()
        
        if self.last_activity_interval:
            pc = PeriodicCallback(self.update_last_activity, 1e3 * self.last_activity_interval)
            pc.start()

        self.log.info("JupyterHub is now running at %s", self.proxy.public_server.url)
        # register cleanup on both TERM and INT
        atexit.register(self.atexit)
        self.init_signal()

    def init_signal(self):
        signal.signal(signal.SIGTERM, self.sigterm)
    
    def sigterm(self, signum, frame):
        self.log.critical("Received SIGTERM, shutting down")
        self.io_loop.stop()
        self.atexit()
    
    _atexit_ran = False
    def atexit(self):
        """atexit callback"""
        if self._atexit_ran:
            return
        self._atexit_ran = True
        # run the cleanup step (in a new loop, because the interrupted one is unclean)
        IOLoop.clear_current()
        loop = IOLoop()
        loop.make_current()
        loop.run_sync(self.cleanup)
        
    
    def stop(self):
        if not self.io_loop:
            return
        if self.http_server:
            if self.io_loop._running:
                self.io_loop.add_callback(self.http_server.stop)
            else:
                self.http_server.stop()
        self.io_loop.add_callback(self.io_loop.stop)
    
    @gen.coroutine
    def launch_instance_async(self, argv=None):
        try:
            yield self.initialize(argv)
            yield self.start()
        except Exception as e:
            self.log.exception("")
            self.exit(1)
    
    @classmethod
    def launch_instance(cls, argv=None):
        self = cls.instance()
        loop = IOLoop.current()
        loop.add_callback(self.launch_instance_async, argv)
        try:
            loop.start()
        except KeyboardInterrupt:
            print("\nInterrupted")

NewToken.classes.append(JupyterHub)

main = JupyterHub.launch_instance

if __name__ == "__main__":
    main()
